1. Field of the Invention
The invention is directed to nebulizers and, more particularly to an intra-oral nebulizer.
2. Description of the Prior Art
Inhalation is a very old method of drug delivery. In the twentieth century it became a mainstay of respiratory care and was known as aerosol therapy. Use of inhaled epinephrine for relief of asthma was reported as early as 1929, in England. Dry powder inhalers have been utilized to administer penicillin dust to treat respiratory infections. In 1956, the first metered dosed inhaler was approved for clinical use.
The scientific basis for aerosol therapy developed relatively late, following the 1974 Sugar Loaf conference on the scientific basis of respiratory therapy.
A more complete history of the development of aerosol therapy and the modern nebulizer is described in the 2004 Phillip Kitridge Memorial Lecture entitled, “The Inhalation of Drugs: Advantages and Problems by Joseph L. Row; printed in the March 2005 issue of Respiratory Care, vol. 50, no. 3.
The typically used modern nebulizer is delivered as a kit of seven plastic pieces which are assembled prior to use to provide for delivery of the medication to a patient via inhalation. An exploded view of the seven pieces showing their relationship for assembly is given in FIG. 1. There is a mouthpiece 100 that is force fit onto one end of a T connector 110. Similarly, the other end of the T connector 110 is attached to a flex tube 120, also by force fit. The parts are such that the components can be assembled and disassembled with a simple twisting action. Nevertheless, when engaged and pressed together, the pieces form a substantially airtight seal. The bottom part of the T connector 110 is connected to a cup cover 130. That, too, is connected by pushing the cup cover onto the bottom part of the T connector in such a way that the airtight seal is formed. The cup cover 130 has a screen 135 that screens the material going into the T connector. There is a cup 150 for receiving the medicine to be nebulized. The cup also has a venturi projecting through the bottom.
In a typical use, a vial containing the medication for administration through the nebulizer is opened and poured into the cup 150 where it accumulates at the edges of the rounded bottom of the cup. The venturi is surrounded by a conical plastic piece through which it passes. The shape of the conical piece of the medicine cup 150 matches substantially the shape of the venturi cover 140. Once the medicine is poured into the cup, the venturi cover 140 is placed over the venturi and the filled medicine cup is screwed, using threaded portions on each piece, onto the cup cover 130. In this way, the medicine is held in place ready for administration.
In use, the bottom of the airline feeding the venturi in the medicine cup is attached to an air hose 160, to which is applied to a source of air pressure thus activating airflow through the venturi. By venturi action, the exhaust of the air flow through the small opening of the venturi results in a reduction in pressure on the downstream side of the airflow so that the medicine from the medicine cup is fed under positive pressure up in the interstices between the conical shape of the medicine cup and the venturi cover and is exhausted then through the screen 135 into the bottom of the T connector 110.
A patient is asked to inhale the aerosol mist provided through the cup cover screen into the airflow channel between the mouthpiece 100 and the flex tube 120. As a patient takes the mouthpiece 100 in their mouth, and inhales, air flows through the open end of the flex tube 120, through the T connector 110, picking up the aerosol medication and into the patients' air passages through the mouthpiece 100.